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Anyone who has been driving for a reasonable length of time will have almost certainly experienced the sinking feeling that comes with finding out that your vehicle has a flat battery. An automobile battery should have an average life of somewhere between five to seven years if correctly maintained.

Further down the line you will have to find out why this has happened, what has caused the battery to fail, is it just flat or is it dead? For now, however, your main objective will be to get the thing started up again so that you can be on your way and complete your journey.

One solution, if you have the muscle available, or if you are at the top of a hill, facing downwards, you could try the good old fashioned “bump start” which involves putting the vehicle in gear and, when you’ve built up enough momentum, releasing the clutch quickly, hence the bump.

If you are doing a hill descent version of the bump start, and it doesn’t work, your options have just been reduced, unless you can push the car up the hill again without doing damage to yourself – so it now becomes even more likely that you are going to have to resort to the most popular method for starting a vehicle with a flat battery, using jumper cables.

It’s at times like this when it is more than helpful to know how to hook up jumper cables properly.

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Surely it Can’t be that Difficult to Hook Up Jumper Cables Properly?

True, it isn’t difficult, but it is surprising how many people don’t know how to do it. What’s more important however are the unpleasant, and even dangerous, things that can happen if you don’t do it right.

Automobile batteries pack a punch! Short circuits can be dangerous with sparks flying all over the place causing a risk to you and a risk of fire and damage to the vehicle. Avoid at all costs.

Here’s our quick, at a glance, checklist of things to do in order to hook up jumper cables properly, and safely.

First of all, check that you have everything you need in order to jump start your vehicle.

Don’t worry, the list is a short one!

  • A pair of jumper cables. These are usually supplied as a set with one red cable and one black cable, each being fitted with color-coded heavy-duty spring loaded crocodile clips at each end. Jumper cables need to be a decent length because it isn’t always possible to get the two vehicles directly next to each other when you want to link them together with the cables.
  • A “Donor” Vehicle. This should be a vehicle with a fully charged battery that can be placed near enough to the car that has the flat battery, which we shall refer to as the “casualty” vehicle.
  • Make sure that both batteries are 12v – most are but it’s worth checking.
  • Take a look at the batteries, especially the casualty, to ensure that there are no leaks, splits and that they are firmly connected to the vehicle’s terminals.

If you are one of those super-prepared motorists you may want to think about purchasing a “booster pack”, which is a powerful rechargeable battery unit with jumper cables attached so that you can jump start your vehicle without having another vehicle available. Most are equipped with a torch so that you can even rescue yourself at night.

Related Post: Best Jump Starters

How to Hook Up the Jumper Cables

The golden rule, when connecting two batteries together, is to avoid a short circuit. This will cause sparks to fly and can easily damage a battery, not to mention the car itself and the possibility of injury to yourself. A short circuit can occur if either of the cables touches the connector on the opposite color coded cable, i.e. if the connector on the red cable touches the connector on the black cable.

As the black cable is usually connected to earth on a motor vehicle you should take extra care to avoid touching any metallic part of either vehicle with the exposed connector on the live, red, cable as this would cause a short circuit.

Since damaged batteries can release fumes it is important not to smoke.

The Sequence for Connecting the Cables is as Follows:

  • Turn off both engines leaving keys in the off position if applicable
  • Turn off all devices that might be using power, e.g. radios, sat nav units, lights etc on both vehicles.
  • Try to get the two vehicles as close together as possible but not actually touching.
  • Attach the connector on one end of the red jumper cable to the positive terminal on the battery that is flat. Positive terminals are always color coded red in some way, possibly with a red plastic cover over the bare terminal. This is the positive terminal of the battery and will usually have a “+” symbol somewhere close.
  • Then carefully attach the other end of the red jump lead directly to the positive terminal of the working battery on the donor vehicle. It is very important not to touch any part of the vehicle with the exposed end of the red cable as this could cause a short circuit.
  • Then attach the connector on the end of the black cable to the negative, black, terminal of the donor, battery.
  • Finally, you should connect the other end of the black, negative, jumper cable to a part of the casualty vehicle with the flat battery that is a good earth point such as a metal part of the engine or something similar.
  • Check that both vehicles are in neutral or “Park” position and that the handbrakes are engaged.
  • When the cables are connected as described above it is time to start the engine of the vehicle with the good battery, i.e. the donor vehicle.

Once the donor vehicle is running successfully for a minute or two you can try to start the vehicle with the flat battery. If, after a few attempts, it doesn’t start then the situation might be more involved than just a simple flat battery and it is likely that professional help will be required.

If the “casualty” vehicle does start, try to resist the temptation to drive away straightaway. Even if everything is running properly it can take around thirty minutes to charge a battery from being totally flat and, if you drive away too soon and stall the engine then you could be right back at square one again.

Related Post: Best Car Battery Chargers

Sources:

  1. How to Use Jumper Cables – How Stuff Works
  2. How to Jump Start a Car Battery – Meineke

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